The inventions disclosed herein relate to various GaN semiconductor devices, including those with a selective etching low-temperature buffer, and related methods for growing single crystal III-V compound semiconductor layers, including those where such layers include nitrides.
For a number of years high quality GaN semiconductor and related semiconductor layers have been sought for the production of semiconductor devices for optical and electronic devices. Recently the need for these layers has been amplified in light emitting devices, such as light emitting diodes (LEDs) and laser diodes (LDs). These devices have applications in displays, optical storage, and others. GaN and its related semiconductors have been used to produce UV, blue, green, red LEDs and UV and near UV lasers. The LEDs using GaN materials have been widely used in large indoor/outdoor displays, traffic signals, local lighting and others. Lasers using GaN materials tend to have life spans on the order of hundreds of hours. It is desirable that such devices have a lifespan of about 10,000 or more hours to be practicable in consumer electronics. The short lifetime in GaN lasers is due to the increased defects in the initial GaN layer which results in defects being transported to light emitting layers.
A usual GaN device structure consists of multiple layers of different type of materials and is built using epitaxial methods. Each layer requires near perfect crystal structure. Since there is no lattice matched substrate materials available for GaN material, GaN materials has to be grown in lattice mismatch substrate such as sapphire, SiC and etc. Thus, initial GaN layer grown has high defect density caused by lattice mismatch. The defects generated in initial GaN growth will propagate into sequential layers resulting in high defect density in critical layers for devices. The defects in critical layers of the device are detrimental to lifetime. Thus there is a need for initial GaN layer in mismatched substrate having low densities of defects being producible through conventional and reasonably inexpensive methods.
U.S. Pat. No. 5,563,422 and related U.S. Pat. Nos. 5,767,581; 5,877,558 and 6,093,965 describe GaN based semiconductor devices, some of which are light producing. U.S. Pat. No. 5,578,839 and related U.S. Pat. Nos. 5,880,486 and 6,078,063 also describe GaN light-emitting semiconductor devices. U.S. Pat. No. 5,689,123 and related U.S. Pat. No. 5,689,123 describe III-V arsenide-nitride semiconductor devices. U.S. Pat. No. 5,739,554 and related U.S. Pat. No. 6,120,600 describe light emitting diodes having a GaN active layer. U.S. Pat. No. 5,751,752 and related U.S. Pat. No. 6,115,399 light emitting semiconductor devices using GaN based compounds. U.S. Pat. No. 5,886,367 describes a epitaxial wafer and a light emitting devices using the same. U.S. Pat. No. 5,987,048 and related U.S. Pat. No. 6,118,801 describe GaN based semiconductor lasers. U.S. Pat. No. 5,945,689 describes light emitting devices using group III nitride compounds. U.S. Pat. No. 5,970,080 describes GaN light emitting elements and methods of manufacture. U.S. Pat. No. 5,981,977 describes nitride compound semiconductor light emitters and methods of manufacture. U.S. Pat. No. 6,005,258 also describes GaN based light emitting semiconductor devices. U.S. Pat. No. 6,017,807 describes P-type GaN semiconductor devices and methods of manufacture. U.S. Pat. No. 6,020,602 also describes GaN based light emitting devices and methods of manufacture. U.S. Pat. No. 6,027,992 describes GaN semiconductor devices and methods of manufacture. U.S. Pat. No. 6,028,887 describes a GaN semiconductor laser having an AlGaN cladding layer. U.S. Pat. No. 6,033,490 describes methods of growing GaN layers on quartz substrates. U.S. Pat. No. 6,043,140 describes methods of manufacturing nitride compound semiconductor including GaN. U.S. Pat. No. 6,051,849 discloses structures having an underlying gallium nitride layer, a patterned layer, and a vertical and lateral gallium nitride layer having a low disclocation density. U.S. Pat. No. 6,067,309 also describes a GaN light-emitting semiconductor device. U.S. Pat. No. 6,069,021 describes semiconductor devices including group III nitride crystal layers and methods of manufacture. U.S. Pat. No. 6,069,440 describes a nitride compound light emitting device having a garnet fluorescent phosphor. U.S. Pat. No. 6,072,189 describes group III light-emitting diodes and laser diodes on a sapphire substrate. U.S. Pat. No. 6,078,064 describes an InGaN light emitting diode. U.S. Pat. No. 6,091,083 describes a GaN semiconductor light emitting device having a non-flat buffer layer. U.S. Pat. No. 6,093,952 describes a high-power GaN schottky rectifier. U.S. Pat. No. 6,100,106 describes processes of the manufacture of nitride based semiconductor light emitting devices. U.S. Pat. No. 6,110,809 describes the manufacture of wafers with group III metal nitride epitaxial layers. U.S. Pat. No. 6,111,275 describes GaN compound semiconductor light emitting devices and methods of manufacture. U.S. Pat. No. 6,111,277 describes light emitting semiconductor devices having mask layers to prevent threading dislocations from propagating to successive semiconductor layers during manufacture. U.S. Pat. No. 6,113,985 describes the manufacture of group III nitride targets for use in sputtering and similar equipment. U.S. Pat. No. 6,121,636 describes a GaN light emitting diode having a reflective film to prevent the infiltration of light to mounting adhesive. U.S. Pat. No. 6,121,637 describes a packaged light emitting semiconductor device. All of the above U.S. patents in their entirety are hereby incorporated by reference.
Included in the invention are laminates having layers of group III-V materials having low dislocation densities, semiconductor devices fabricated using low dislocation density group III-V layers, and methods for making these structures.
In the inventions, it is desired to provide methods for growing one or more group III-V compound semiconductor layers of nitrides having low dislocation densities on a substrate that has a large lattice mismatch compared with GaN and other group III-V compounds. Some of the inventions are concerned with GaN layers, GaN semiconductor devices, and semiconductor lasers fabricated from GaN materials.